The present invention relates generally to magnetic component devices for electronic circuits, and more particularly to devices such as inductors and transformers for mounting on circuit boards.
Conventional magnetic devices such as inductors and transformers typically include one or more conductive windings positioned about a bobbin or other winding spool. The windings may include primary and secondary windings in a transformer, or may include one or more windings in an inductor. Magnetic devices of this nature in some applications include multiple windings, or coils, positioned around the bobbin. Each winding includes one or more turns of a conductive wire covered with insulation around the bobbin. Conventional circuits for electronic applications such as power supplies and power converters, as well as other electronic components, often include high-voltage circuit regions and low-voltage circuit regions. In many applications it is desirable to include one or more magnetic components associated with the high-voltage circuit region and to also include one or more magnetic components associated with the low-voltage circuit region.
However, because magnetic components are often the largest circuit items in an electronic device, cost considerations and layout efficiency make it desirable to combine the high-voltage and low-voltage windings on a single magnetic component in many applications. Others have attempted to overcome the cost and layout efficiency problems of conventional winding configurations by placing both low-voltage and high-voltage windings on a single bobbin structure on a magnetic component. However, voltage effects between the windings can cause undesirable performance such as noise, magnetic coupling and efficiency losses. Such conventional configurations provide little voltage isolation between the high-voltage and low-voltage windings because the windings are both positioned on the same bobbin in close proximity.
Another problem associated with multiple-winding magnetic components is winding placement. Conventional winding configurations that place main and auxiliary windings about a single bobbin structure include winding tolerances that may lead to inconsistent placement of the windings relative to each other and relative to the bobbin. This may lead to inconsistent magnetic coupling between the high-voltage main winding and the lower-voltage auxiliary windings, causing variance in performance between components. Additional problems with multiple windings on a single bobbin structure include high potential failures between windings, especially in high voltage applications. Such failures may lead to device malfunction and risk of fire.
To further overcome the problems with conventional winding configurations, others have developed low-profile magnetic devices that use planar windings disposed on a printed circuit board. Conventional printed winding board circuits include one or more winding loops formed as conductive traces on a printed circuit board. Multiple boards may be stacked and electrically connected to form multi-loop magnetic devices. However, conventional printed winding boards for magnetic devices are limited in the number of loops or turns that may be printed on the winding board substrate. For this reason, conventional printed winding boards are generally limited to relatively low-voltage applications as compared to bobbin-wound magnetic components used for higher-voltage applications.
What is needed then are improvements in magnetic component devices, wiring configurations, and associated methods for positioning high-voltage and low-voltage windings on a single magnetic component device.